Since there's been a big influx from Twitter, here's an updated and shorter version of a Mastodon primer I wrote back in 2018.

For more detail on how federation works, see Elilla's Futuristic Mastodon introduction for 2021.

Get off

There's, which is run by the lead developer of the Mastodon server software, and it's usually the biggest in terms of users.

Then there's the rest of the Fediverse, hundreds of smaller instances which are focused around different themes. Some are regional, like, which is where I mostly hang out - some are themed around a particular hobby or professional interest, or parenting, or sexuality, or political slant. Some just won't let you post the letter 'e'.

There are a couple of advantages to being on a small instance: it's not possible to do good moderation at the scale of

Other advantages are a local timeline which moves slow enough to take in, so you can hang out and discover new people.

And there are also forks of the main codebase with new features. Some of these are just for fun, like, but there are also forks like Hometown which provide features which are conducive to smaller, community-based instances, like local-only posts that can't be seen from other instances.

I wouldn't worry too much about which instance to pick - just have a look at their moderation policy and user profiles page and go with what seems good. Migrating to another instance is not as much fuss as it used to be if you change your mind.

Oh, I almost forgot: instances can have custom emojis! This is important! You can see what emojos are available on a given instance here!

Also you can have accounts on multiple instances, and good clients like Toot! provide easy ways to switch between accounts.

Content warnings are good, actually

I'm so habituated to Mastodon's culture of content warnings that in the last election when I saw too many photos of Scott Morrison I'd instinctively think "cw that shit". Here's a list of some of the things you should probably cw:

  • alcohol and drug use
  • food and whether or not it's veg/vegan
  • descriptions of or allusions to violence
  • references to current events, politics and media
  • spoilers, vague or specific
  • profanity
  • stuff you are an expert in or hyperfixated on but which might bore other people
  • as the setup to a joke
  • lewd or explicit sexual content
  • AI-generated imagery
  • self-promotion, ie links to your blog posts
  • references to physical or mental illness
  • exercise and fitness
  • eye contact in photos (important for neurodivergent folks)

The way I think about this is that it's putting the choice in the hands of the person who's reading your post, rather than trying to get in people's face all the time.

Writing descriptions for images and audio/video content is also recommended.

Unlisted by default

Mastodon's post visibility is pretty fine-grained:

  • public
  • unlisted
  • followers-only
  • direct message

The difference between public and unlisted is that the latter doesn't appear in public timelines or searches. It's considered polite to have bots posting as unlisted so that timelines on small servers don't get crowded, and I tend to post as unlisted by default myself. I think it makes things less shouty.

And if you think content warnings get in the way of your shitposts, set them to followers-only, until your followers tell you to put a sock in it.

It isn't going to be Twitter

One of the big tensions in the fediverse is between the communities of coders and users of small instances, and, which is showing bad signs of wanting to be the Next Big Thing, and has a track record of doing things which work against the idea of the Fediverse as a collection of small federated instances - for example, releasing an "offical" Mastodon app which doesn't give you a view of the local timeline.

I've come to think that social media above a certain scale will always end up being bad: the ability to go viral comes at the cost of all the downsides to a service which is too large to properly moderate.

Smaller instances are to some extent ephemeral - sometimes they collapse due to drama, sometimes the moderators and admins get burnt out or can't afford to keep them running. While this is obviously not great for the people involved, I think a community of websites which can keep going as new ones are formed and old ones leave is a lot more promising than one big website run by one guy.